org.apache.bcel.classfile

Class ConstantPool

Implemented Interfaces:
Cloneable, Node, Serializable

public class ConstantPool
extends java.lang.Object
implements Cloneable, Node, Serializable

This class represents the constant pool, i.e., a table of constants, of a parsed classfile. It may contain null references, due to the JVM specification that skips an entry after an 8-byte constant (double, long) entry. Those interested in generating constant pools programatically should see ConstantPoolGen.
Version:
$Id: ConstantPool.java 386056 2006-03-15 11:31:56Z tcurdt $
Author:
M. Dahm
See Also:
Constant, ConstantPoolGen

Field Summary

private Constant[]
constant_pool
private int
constant_pool_count

Constructor Summary

ConstantPool(DataInputStream file)
Read constants from given file stream.
ConstantPool(Constant[] constant_pool)

Method Summary

void
accept(Visitor v)
Called by objects that are traversing the nodes of the tree implicitely defined by the contents of a Java class.
String
constantToString(int index, byte tag)
Retrieve constant at `index' from constant pool and resolve it to a string representation.
String
constantToString(Constant c)
Resolve constant to a string representation.
ConstantPool
copy()
void
dump(DataOutputStream file)
Dump constant pool to file stream in binary format.
private static String
escape(String str)
Constant
getConstant(int index)
Get constant from constant pool.
Constant
getConstant(int index, byte tag)
Get constant from constant pool and check whether it has the expected type.
Constant[]
getConstantPool()
String
getConstantString(int index, byte tag)
Get string from constant pool and bypass the indirection of `ConstantClass' and `ConstantString' objects.
int
getLength()
void
setConstant(int index, Constant constant)
void
setConstantPool(Constant[] constant_pool)
String
toString()

Field Details

constant_pool

private Constant[] constant_pool

constant_pool_count

private int constant_pool_count

Constructor Details

ConstantPool

(package private)  ConstantPool(DataInputStream file)
            throws IOException,
                   ClassFormatException
Read constants from given file stream.
Parameters:
file - Input stream

ConstantPool

public ConstantPool(Constant[] constant_pool)
Parameters:
constant_pool - Array of constants

Method Details

accept

public void accept(Visitor v)
Called by objects that are traversing the nodes of the tree implicitely defined by the contents of a Java class. I.e., the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.
Specified by:
accept in interface Node
Parameters:
v - Visitor object

constantToString

public String constantToString(int index,
                               byte tag)
            throws ClassFormatException
Retrieve constant at `index' from constant pool and resolve it to a string representation.
Parameters:
index - of constant in constant pool
tag - expected type
Returns:
String representation

constantToString

public String constantToString(Constant c)
            throws ClassFormatException
Resolve constant to a string representation.
Parameters:
c - Constant to be printed
Returns:
String representation

copy

public ConstantPool copy()
Returns:
deep copy of this constant pool

dump

public void dump(DataOutputStream file)
            throws IOException
Dump constant pool to file stream in binary format.
Parameters:
file - Output file stream

escape

private static final String escape(String str)

getConstant

public Constant getConstant(int index)
Get constant from constant pool.
Parameters:
index - Index in constant pool
Returns:
Constant value
See Also:
Constant

getConstant

public Constant getConstant(int index,
                            byte tag)
            throws ClassFormatException
Get constant from constant pool and check whether it has the expected type.
Parameters:
index - Index in constant pool
tag - Tag of expected constant, i.e., its type
Returns:
Constant value
See Also:
Constant

getConstantPool

public Constant[] getConstantPool()
Returns:
Array of constants.
See Also:
Constant

getConstantString

public String getConstantString(int index,
                                byte tag)
            throws ClassFormatException
Get string from constant pool and bypass the indirection of `ConstantClass' and `ConstantString' objects. I.e. these classes have an index field that points to another entry of the constant pool of type `ConstantUtf8' which contains the real data.
Parameters:
index - Index in constant pool
tag - Tag of expected constant, either ConstantClass or ConstantString
Returns:
Contents of string reference

getLength

public int getLength()
Returns:
Length of constant pool.

setConstant

public void setConstant(int index,
                        Constant constant)
Parameters:
constant - Constant to set

setConstantPool

public void setConstantPool(Constant[] constant_pool)
Parameters:
constant_pool -

toString

public String toString()
Returns:
String representation.